They're just getting noticed by the next higher level of denizens in this dungeon. Because they're making progress. It's the rule of dungeoneering: the more progress you make, the higher the level of monsters that begin to notice you. Supposedly you will ultimately attract the attention of the Big Bad, which will either end Very Badly for you, or if you're epic enough, you'll defeat and gain the Big MacGuffin he's hoarding.

Man, she's made quite the haul. That's an armful of gold to accompany that pop of gold coins from the trap earlier. Even after splitting it and paying for upkeep (new town portal scroll, some kind of guild tax maybe, room and board) she's had a productive day.

Now it's back to town and tavern. Perhaps meeting up with [the remains of?] her original party? who might merge [we do need more than two permanent PC]
Of course, the loot needs to be banked/spent. Should she get new weapon? armor? scrolls? potions?